Comparative demography of an epiphytic lichen: support for general life history patterns and solutions to common problems in demographic parameter estimation
Comparative demography of an epiphytic lichen: support for general life history patterns and solutions to common problems in demographic parameter estimation
复制标题
附生地衣的比较人口统计学：支持一般生活史模式和人口参数估计中常见问题的解决方案
作者：
R. Shriver;K. Cutler;D. Doak
地衣是许多陆地生态系统的主要组成部分，但其种群生态学充其量只是知之甚少。很少有研究完全量化任何地衣的生活史或人口模式，特别是很少关注附生物种。我们进行了为期6年的人口研究Vulpicida pinastri，附生叶状地衣，在阿拉斯加中南部。在测试了多个大小结构函数来描述每个V. pinastri人口统计率的模式后，我们使用所得的估计值来构建该物种的随机人口统计模型。这个模型的发展使我们提出了两个一般性问题的解决方案，在许多类群的人口模型的建设：如何简单，但准确地描述高度倾斜的增长率，以及如何估计招聘率是非常难以直接观察。我们的研究结果表明，V. pinastri具有快速和可变的生长，对于小个体，存活率低且可变，但这些特征与相当长的寿命相结合（例如，>50年的平均未来寿命为4厘米2的叶状体）和小偏差的随机种群增长率从确定性的期望。我们发现与其他地衣研究的人口模式的比较表明，他们相对简单的架构可能允许更清晰的概括地衣比其他类群的增长模式，并证实了预期的模式更快的增长速度附生物种。
Lichens are major components in many terrestrial ecosystems, yet their population ecology is at best only poorly understood. Few studies have fully quantified the life history or demographic patterns of any lichen, with particularly little attention to epiphytic species. We conducted a 6-year demographic study of Vulpicida pinastri, an epiphytic foliose lichen, in south-central Alaska. After testing multiple size-structured functions to describe patterns in each V. pinastri demographic rate, we used the resulting estimates to construct a stochastic demographic model for the species. This model development led us to propose solutions to two general problems in construction of demographic models for many taxa: how to simply but accurately characterize highly skewed growth rates, and how to estimate recruitment rates that are exceptionally difficult to directly observe. Our results show that V. pinastri has rapid and variable growth and, for small individuals, low and variable survival, but that these traits are coupled with considerable longevity (e.g., >50 years mean future life span for a 4-cm2 thallus) and little deviation of the stochastic population growth rate from the deterministic expectation. Comparisons of the demographic patterns we found with those of other lichen studies suggest that their relatively simple architecture may allow clearer generalities about growth patterns for lichens than for other taxa, and that the expected pattern of faster growth rates for epiphytic species is substantiated.